Blistering diseases

This topic provides a differential diagnosis of blistering skin conditions.

  • Vesicles are less than 5 mm in diameter.
  • A bulla is larger. Note: the plural of bulla is bullae.
  • Old blisters may erode. Exudation causes crust.

The table below considers acute and chronic blistering diseases.

Acute blistering diseases

Acute blistering diseases can be due to infection or inflammatory disorders, and can be generalised or localised to one body site. Generalised acute blistering diseases can be life threatening and often necessitate hospitalisation. Skin biopsy may be helpful in making a diagnosis.

Acute blistering conditions should also be investigated by taking swabs for bacterial and viral culture.

Acute blistering diseases
Generalised infection Localised infection

Chickenpox (varicella)

  • Childhood illness; more serious in adults
  • Scalp, face, oral mucosa, trunk
  • Culture/PCR Herpes varicella zoster

Eczema herpeticum

Atypical enterovirus infection

  • Widespread vesicular eruption
  • Clears in a few days

Necrotising fasciitis

  • Very sick
  • Rapid spread from site of origin
  • Anaesthetic areas


  • Acute febrile illness
  • Swab Streptococcus pyogenes

Herpes zoster (shingles)

  • Dermatomal
  • Culture/PCR Herpes zoster

Herpes simplex

  • Monomorphic, umbilicated
  • Culture/PCR Herpes simplex

Bullous impetigo

  • Rapidly enlarging plaque
  • Swab Staphylococcus aureus
  • Complicates wounds, scabies etc

Enteroviral vesicular stomatitis

  • Hands, feet and mouth
  • Clears in a few days
Non-infectious generalised rash Non-infectious localised rash

Stevens Johnson syndrome / toxic epidermal necrolysis

  • Patient very unwell
  • Mucosal involvement
  • Nearly always drug-induced
  • Rarely due to mycoplasma infection
  • Red skin comes off in sheets

Drug hypersensitivity syndrome

  • Drug started up to 8 weeks prior to onset
  • Morbilliform eruption that may blister
  • Often, mucosal involvement
  • Multiorgan damage
  • Often, marked eosinophilia

Staphylococcal scalded skin syndrome

Erythema multiforme

  • Reaction, eg to infection
  • Acute eruption of papules, plaques, target lesions
  • Acral distribution: cheeks, elbows, knees, hands, feet
  • May involve mucosal surfaces

Acute febrile neutrophilic dermatosis

  • Reaction, eg to infection
  • Pseudovesicular plaques
  • May involve mucosal surfaces


Polymorphic light eruption

  • Affects body sites exposed to sun eg hands, upper chest, feet
  • May spare face
  • Arises within hours of exposure to bright sunlight
See also:


Insect bites and stings

  • Crops of urticated papules
  • Central vesicle or punctum
  • Favour exposed sites


Miliaria crystallina

  • Central trunk
  • Sweat rash
  • Vesicles are very superficial

Acantholytic dermatosis

  • Acute or chronic
  • Elderly males
  • Itchy or asymptomatic
  • Crusted papules

Fixed drug eruption

  • Recurring rash
  • Due to intermittent drug
  • Central blister


  • Fingers, toes
  • Exposed to cold
  • Purplish tender plaques

Chronic blistering diseases

Diagnosis of chronic blistering diseases often requires skin biopsy for histopathology and direct immunofluorescence. A blood test for specific antibodies (indirect immunofluorescence) may also prove helpful in making the diagnosis of an immunobullous disease.

Immunobullous diseases Bullous genodermatoses

Bullous pemphigoid

  • Mainly cutaneous
  • Mostly affects the elderly
  • Often associated stroke or dementia
  • Subepidermal bullae
  • Eczematous or urticarial precursors

Childhood bullous pemphigoid

  • Rare
  • Subepidermal bullae

Cicatricial pemphigoid

  • Mainly mucous membranes
  • Also scalp, neck
  • Subepidermal bullae

Brunsting-Perry variant of cicatricial pemphigoid

  • Localised to scalp, neck

Pemphigoid gestationis

  • Bullous pemphigoid in pregnancy
  • Often, initially periumbilical

Dermatitis herpetiformis

  • Associated gluten sensitive enteropathy
  • Intensely itchy; vesicles often removed by scratching
  • Symmetrical on scalp, shoulders, elbows, knees, buttocks

Linear IgA dermatosis

  • Sometimes, drug-induced
  • Annular blisters (string of pearls)

Epidermolysis bullosa acquisita

  • Subepidermal bullae at site of trauma

Pemphigus vulgaris

  • Mucosal and/or cutaneous especially scalp
  • Superficial blisters, erosions

Pemphigus foliaceus

  • May be drug-induced
  • Scalp, face, upper trunk
  • Superficial blisters, erosions

Paraneoplastic pemphigus

  • Mucosal and cutaneous blisters and erosions
  • Associated with an internal cancer

Other conditions that sometimes blister

See also:

Epidermolysis bullosa

  • Various types
  • Onset at birth or early childhood


  • Various types
  • Often, onset in childhood

Hailey-Hailey (familial pemphigus)

  • Onset usually as adult
  • Flexural

Porphyria cutanea tarda

  • Dorsum hands
  • Follows sun exposure
  • Skin fragility
  • Excessive urinary and faecal porphyrins

Related information

On DermNet NZ:

Other websites:

Books about skin diseases:

See the DermNet NZ bookstore

Author: Dr Amanda Oakley, Dermatologist, Hamilton, New Zealand, 1997. Updated September 2015.

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